Change TextView on content_main.xml in MainActivity.java

Question

I'm using the Android Studio standard template "Navigation Drawer Activity" which contains the content_main.xml layout.

On this layout is my textView which I want to change the text from my MainActivity.java.

I tried following but nothing changes:

LayoutInflater inflater = (LayoutInflater)this.getSystemService (Context.LAYOUT_INFLATER_SERVICE);
            View view = inflater.inflate(R.layout.content_main, null);
            TextView txt = (TextView)view.findViewById(R.id.txt_head);
            txt.setText("sdfsdf");

content_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/relativelayout_for_fragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.example.w4ter.ledcontroldesign.MainActivity"
    tools:showIn="@layout/app_bar_main"
    android:orientation="vertical"
    android:paddingTop="10dp">

    <TextView
        android:text="Presets"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textAppearance="@style/TextAppearance.AppCompat.Headline"
        android:id="@+id/txt_head" />

    <View
        android:layout_width="fill_parent"
        android:layout_height="1dip"
        android:background="#61000000" />
</LinearLayout>

Answer 1

there is no need of LayoutInflater. Simply use:

TextView textView = (TextView) findViewById(R.id.txt_head);
texView.setText("Hello");

Hope this helps.

Answer 2

You just need to access the TextView component the normal way. With that template the content_main.xml is included inside the main layout, so you sould do as follows in your main activity (maybe inside the onCreate method or wherever you need):

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {

    //...

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        TextView txt = (TextView)view.findViewById(R.id.txt_head);
        txt.setText("sdfsdf");
    }

    //...
}

Assuming that you have a app_bar_main.xml inside the main layout wich contains the content_main.xml. In the end everything is accessible from the main activity directly since the layouts are included in the main layout.

Hope it helps!